Torsion (twisting): Lumbar

Twisting can exert enough force on both discs and SI joints to be of concern. It is particularly risky to add any extra force to the twist, by either an adjustment from the teacher, or, as it may happen in Ardha Matsyendrasana by using the front arm to press against the opposite leg to increase the degree of the rotation.

The spine is most stable and able to support load when it maintains its natural curves (neutral spine.)

The further it gets from that position, the more vulnerable it becomes. Although the pose depicted to the left looks effortless, the arm-knee levering is pulling the pelvis and lower back out of neutral, causing a tension-compression-torsion action on the vertebral joints and increasing the stress to the SI joints and lower back. The unevenness in the positioning of the sitting bones leads to a shear strain between the sacrum and the illium bones. The regular practice of the posture shown above, would therefore result in a slow loosening of the ligaments in the SI joints region. If the ligaments are already loose, performing the pose could result in getting the SI joint itself out of alignment.

For extremely flexible bodies like the model above the pose can be attained by just resting the arm against the knee without using it to press in order to increase the twist. This will not be possible for less flexible bodies.

If a twist (either sitting or standing) is practiced with an aligned spine and using only the trunk muscles to execute rotation, as shown belowthe risk of injury to discs and SI joints is extremely low.

The arms should never be used as leverage to increase the range of spinal rotation.

Sitting Twist Use the abdominal muscles to avoid excessive twist at the lumbar spine and the breath to engage the mid and upper thoracic expansion.

Parivrtta Trikonasana Using the bottom arm to ground as theupper body opens and rotates.

In the full pose shown below the outstretched arms stabilize the shoulders and upper trunk, while the legs are lowered from an initial position perpendicular to the floor, to either side. During the movement, feet and ankles are held together, resulting in the pelvis being rotated 90 degrees in relation to the shoulders.The weight of the legs acts as a lever, and because of their length and the relatively long distance to the origin of the rotation, just above the sacrum, very high levels of torsion can develop along the spine and in the SI joints. Proper stabilization is essential, especially for the SI joints and at the L1-T12 junction, where the concave lumbar meets the convex thoracic spine.

The postures below show examples of how the pose can be made safer. Bending the knees and/or restricting the range of movement of the legs by putting some support (a bolster or blocks) under them, will reduce the degree of twist and associated torsional forces on the spine and uneven pull on the SI joints.

​A bolster is used to restrain the amount of turning and twisting of the spine.

​Knees are bent to decrease the load on the spine while rotating, but the range of the twist is the same as in the original pose.